scholarly journals Behavior of Square RC Short Columns with New Arrangement of Ties Subjected to Axial Load: Experimental and Numerical Studies

2022 ◽  
Author(s):  
Hazem Elbakry ◽  
Tarek Ebeido ◽  
El-Tony M. El-Tony ◽  
Momen Ali
Keyword(s):  
Reinforced Concrete ◽  
Axial Load ◽  
Concrete Columns ◽  
Experimental Program ◽  
Transverse Reinforcement ◽  
Reinforcing Bars ◽  
Rc Columns ◽  
Reinforced Concrete Columns ◽  
Short Columns ◽  
Numerical Studies

Reinforced concrete columns consume large quantities of ties, especially inner cross-ties in columns with large dimensions. In some cases, nesting of the pillars occurs as a result of the presence of cross-ties. The main objective of this paper is to develop new methods for transverse reinforcement in RC columns and investigate their effect on the behavior of the columns. The proposed V-ties as transverse reinforcement replacing the ordinary and cross-ties details are economically feasible. They facilitate shorter construction periods and decrease materials and labor costs. For this purpose, experimental and numerical studies are carried out. In the experimental program, nine reinforced concrete columns with identical concrete dimensions and longitudinal reinforcing bars were prepared and tested under concentric axial load with different tie configurations. The main parameters were the tie configurations and the length (lv) of V-tie legs. As part of the numerical study, the finite element model using the ABAQUS software program obtained good agreement with the experimental results of specimens. A numerical parametric study was carried out to study the influence of concrete compressive strength and longitudinal reinforcement ratio on the behavior of RC columns with the considered tie configurations. Based on the experimental and numerical results, it was found that using V-tie techniques instead of traditional ties could increase the axial load capacity of columns, restrain early local buckling of the longitudinal reinforcing bars and improve the concrete core confinement of reinforced concrete columns.

scholarly journals The use of Grade 380 steel for transverse confining reinforcement in columns

1987 ◽  
Vol 20 (2) ◽  
pp. 99-115
Author(s):  
F. A. Zahn ◽  
R. Park ◽  
M. J. N. Priestley
Keyword(s):  
Reinforced Concrete ◽  
Axial Load ◽  
Analytical Study ◽  
Concrete Columns ◽  
Lateral Loading ◽  
Transverse Reinforcement ◽  
Reinforced Concrete Columns ◽  
Ductility Factor ◽  
Strain Behaviour ◽  
Curvature Ductility

The results of recent experimental and analytical studies of the stress-strain behaviour of concrete confined by New Zealand manufactured Grade 275 or Grade 380 reinforcing steel are presented. First, the behaviour of three pairs of concentrically loaded reinforced concrete columns containing spirals from either Grade
275 or Grade 380 steel are compared, including the stage at which spiral fracture occurred. Second, the results of tests on four reinforced concrete columns containing Grade 380 spiral or rectangular hoop reinforcement and subjected to combined axial
load and cyclic lateral loading are reported. An analytical
study which was conducted to determine the available curvature ductility factor at the stage of fracture of the transverse reinforcement is described. The results are used to give a guideline for the safe use of Grade 380 steel as transverse confining reinforcement.

scholarly journals Shear Strength Model for Reinforced Concrete Columns with Low Transverse Reinforcement Ratios

2014 ◽  
Vol 17 (10) ◽  
pp. 1373-1385 ◽  
Author(s):  
Cao Thanh Ngoc Tran ◽  
Bing Li
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Axial Load ◽  
Concrete Columns ◽  
Transverse Reinforcement ◽  
Reinforced Concrete Column ◽  
Reinforced Concrete Columns ◽  
Existing Structures ◽  
Reversed Cyclic ◽  
Constant Axial Load

This paper introduces an equation developed based on the strut-and-tie analogy to predict the shear strength of reinforced concrete columns with low transverse reinforcement ratios. The validity and applicability of the proposed equation are evaluated by comparison with available experimental data. The proposed equation includes the contributions from concrete and transverse reinforcement through the truss action, and axial load through the strut action. A reinforced concrete column with a low transverse reinforcement ratio, commonly found in existing structures in Singapore and other parts of the world was tested to validate the assumptions made during the development of the proposed equation. The column specimen was tested to failure under the combination of a constant axial load of 0.30 f' c A g and quasi-static cyclic loadings to simulate earthquake actions. The analytical results revealed that the proposed equation is capable of predicting the shear strength of reinforced concrete columns with low transverse reinforcement ratios subjected to reversed cyclic loadings to a satisfactory level of accuracy

scholarly journals Near-field explosion effects on reinforced concrete columns: an experimental investigation

2018 ◽  
Vol 45 (4) ◽  
pp. 289-303 ◽  
Author(s):  
Abass Braimah ◽  
Farouk Siba
Keyword(s):  
Reinforced Concrete ◽  
Experimental Testing ◽  
Near Field ◽  
Axial Loading ◽  
Concrete Columns ◽  
Load Level ◽  
Experimental Program ◽  
Rc Columns ◽  
Reinforced Concrete Columns ◽  
Scaled Distance

Explosion effects on structures have been an area of active research over the past decades. This is due to the increasing number of terrorists’ action against infrastructures. Although significant amount of work is continuing on the effects of explosions on infrastructures, experimental work involving live explosion testing is limited. Moreover, experimental testing of reinforced concrete (RC) columns subjected to near-field explosions is scant. This paper presents results of an experimental program designed to investigate the effects of near-field explosions on RC columns with different tie spacing and at different scaled distances. The results show that the response of columns is strongly dependent on scaled distance. As the scaled distance increased the severity of damage reduced; seismic columns showed better response. The effect of axial loading was also observed to increase the level of damage on reinforced concrete columns at the axial load level and blast loads considered in the test program.

Study of the residual axial capacities of shear-damaged reinforced concrete columns: Part 2—experimental verification of an evaluation model

2018 ◽  
Vol 22 (2) ◽  
pp. 459-472
Author(s):  
Yong Yang ◽  
Kazuto Matsukawa ◽  
Ho Choi ◽  
Yoshiaki Nakano
Keyword(s):  
Reinforced Concrete ◽  
Evaluation Model ◽  
Concrete Columns ◽  
Experimental Program ◽  
Transverse Reinforcement ◽  
Concrete Core ◽  
Reinforced Concrete Columns ◽  
Damage Pattern ◽  
Axial Capacity ◽  
Proposed Model

This article presents an experimental program to further verify the arch resistance model, which was proposed for evaluating the residual axial capacities of shear-damaged reinforced concrete columns in part 1 of the companion papers. Three reinforced concrete columns with different transverse reinforcement ratios are designed and tested up to axial collapse under different axial force levels. Based on the experimental results, the transverse reinforcement within the shear-damaged region of the designed specimens is confirmed to be able to fully develop their strength at axial collapse. With regard to the evaluation of residual axial capacities, when the damage pattern of the concrete core is consistent with that described in the proposed model, the residual axial capacity of the column along with the included two contributions of the concrete core and longitudinal bars are estimated with a high level of accuracy. When the damage pattern of the concrete core is not completely consistent with that described in the proposed model, although the contribution of the concrete core is not accurately estimated, the contribution of the longitudinal bars is still accurately evaluated. Furthermore, because of the low percentage of the contribution of the concrete core, the damage pattern of the concrete core has little effect on the evaluation accuracy of the residual axial capacity of the column. Thus, using the proposed model, the residual axial capacities of the columns with slightly different damage patterns of the concrete core are still estimated with a high accuracy in this experimental program.

scholarly journals Analytical Estimation of the Residual Drift of Reinforced Concrete Columns under the Ultimate Displacement Capacity

2020 ◽  
Author(s):  
Sinan Cansız
Keyword(s):  
Reinforced Concrete ◽  
Axial Load ◽  
Concrete Columns ◽  
Load Level ◽  
Transverse Reinforcement ◽  
Longitudinal Reinforcement ◽  
Reinforced Concrete Columns ◽  
Residual Drift ◽  
Drift Ratio ◽  
Ultimate Displacement

Reinforced concrete columns are the most important structural elements that determine the ductility of the structures. The main parameters affecting the behavior of reinforced concrete columns are axial load level, shear span, percent of longitudinal reinforcement and percent of transverse reinforcement. The aim of this study is to examine residual damage behavior of RC columns under cyclic loading similar to the earthquake loads combined depend on variable axial load level, spanning to depth ratio, longitudinal reinforcement ratio and transverse reinforcement ratio. When the results of experiments are examined, it can be seen that the residual drift ratio of reinforced concrete columns can be used to characterize the damage occurred in the structure after earthquake or loading. In addition, the performance level of the reinforced concrete columns according to the residual drift ratio is defined in FEMA356. As a result of this study, the analytical equation that calculates the residual drift ratio of the reinforced concrete columns at the ultimate displacement limit is proposed.

scholarly journals Behavior of Columns Confined With FRP Fabrics under Repeated Lateral Loads

2019 ◽  
pp. 1-19
Author(s):  
Hesham A. Haggag ◽  
Nagy F. Hanna ◽  
Ghada G. Ahmed
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Axial Load ◽  
Axial Loading ◽  
Concrete Columns ◽  
Fiber Reinforced Polymers ◽  
Lateral Loads ◽  
Reinforced Concrete Columns ◽  
Reinforced Polymers ◽  
Axial Capacity

The axial strength of reinforced concrete columns is enhanced by wrapping them with Fiber Reinforced Polymers, FRP, fabrics.  The efficiency of such enhancement is investigated for columns when they are subjected to repeated lateral loads accompanied with their axial loading.  The current research presents that investigation for Glass and Carbon Fiber Reinforced Polymers (GFRP and CFRP) strengthening as well.  The reduction of axial loading capacity due to repeated loads is evaluated. The number of applied FRP plies with different types (GFRP or CFRP) are considered as parameters in our study. The study is evaluated experimentally and numerically.  The numerical investigation is done using ANSYS software. The experimental testing are done on five half scale reinforced concrete columns.  The loads are applied into three stages. Axial load are applied on specimen in stage 1 with a value of 30% of the ultimate column capacity. In stage 2, the lateral loads are applied in repeated manner in the existence of the vertical loads.  In the last stage the axial load is continued till the failure of the columns. The final axial capacities after applying the lateral action, mode of failure, crack patterns and lateral displacements are recorded.   Analytical comparisons for the analyzed specimens with the experimental findings are done.  It is found that the repeated lateral loads decrease the axial capacity of the columns with a ratio of about (38%-50%).  The carbon fiber achieved less reduction in the column axial capacity than the glass fiber.  The column confinement increases the ductility of the columns under the lateral loads.

SEISMIC PERFORMANCE OF GFRP-RC RECTANGULAR COLUMNS: NUMERICAL STUDY

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Ehab El-Salakawy ◽  
Fangxin Ye ◽  
Yasser Mostafa Selmy
Keyword(s):  
Reinforced Concrete ◽  
Cyclic Loading ◽  
Axial Load ◽  
Numerical Study ◽  
Concrete Strength ◽  
Weight Ratio ◽  
Concrete Columns ◽  
Load Level ◽  
Reinforced Concrete Columns ◽  
Rectangular Columns

Composite materials like glass fiber-reinforced polymer (GFRP) is becoming widely acceptable to be used as a reinforcing material due to its high ultimate tensile strength-to-weight ratio and excellent resistance to corrosion. However, the seismic behavior of GFRP-reinforced concrete columns has not been fully investigated yet. This paper presents the results of a numerical analysis of full-size GFRP-RC rectangular columns under cyclic loading. The simulated column depicts the lower part of a building column between the foundation and the point of contra-flexure at the mid-height of the column. GFRP reinforcement properties and concrete modeling based on fracture energy have been incorporated in the numerical model. Experimental validation has been used to examine the accuracy of the constructed finite element models (FEMs) using a commercially available software. The validated FEM was used to perform a parametric study, considering several concrete strength values and axial load levels, to study its influence on the performance of the GFRP-reinforced concrete columns under cyclic loading. It was concluded that the hysteretic dissipation capacity deteriorates under high axial load level due to severe softening of the concrete. The FE results showed a substantial improvement of the lateral load-carrying capacities by increasing concrete compressive strength.

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